This invention relates to electroexplosive devices.
Electroexplosive devices are used in ordinance systems to ignite an explosive or pyrotechnic mixture. The devices typically comprise a semiconductor chip in contact with the explosive mixture. (See, for example, U.S. Pat. No. 3,366,055 issued to Hollander, Jr.) When a firing voltage is applied to the chip, the temperature rise generated is sufficient to ignite the mixture. Two important characteristics of the chips are that they exhibit high reliability in firing and that they prevent stray RF fields and induced arcing from igniting the mixture.
One problem associated with such devices is that, if cracks develop the chips, RF immunity is decreased and misfires could occur. Such cracks are not easily detected since many times the I-V curves of the chips would remain the same even after cracks developed. Thus, it is desirable to provide chips with improved crack detection.
In addition to crack detection, it is desirable to be able to fire the chip in a small predetermined area in order that the firing energy is discharged in close proximity to the mixture.
U.S. Pat. No. 5,085,146 issued to Baginski shows an electroexplosive device using a semiconductor chip with p-type dopants diffused into both major surfaces. In one embodiment (FIG. 3), the p-type dopants are formed at the center the chip and extend in "corridors" out to and including the edge of the chip. In a further embodiment (FIGS. 4 and 5), the p-type region on one surface is isolated at the center of the chip. Schottky barrier junctions are also disclosed. It is recognized that the leakage currents through the p-n junction can be used to test the chip.
U.S. Pat. No. 4,8 19,560, issued to Patz et al., also shows a chip for an igniter which includes a diffused diode portion, or a transistor portion.